There are numerous applications in industrial, field and home installations requiring valves, meters or other devices positioned in pipe distribution systems. These control or metering devices are often located within a pipe casing for convenience and protection. Underground water distribution lines are one example of such usage. Valves employed to control the water flow are often below ground and provision of a surrounding pipe casing prevents dirt and debris from destroying the operability of the valve. Access to the pipe enclosed valve stem is afforded by a portable T-wrench. The protective pipe casing may terminate flush with ground level or extend above ground as a riser. There are other applications in which flow meters are similarly installed. In other situations, a section of pipe is used to permit access for inspection or provide a means of venting or sounding of tanks.
Ground level open pipe terminations pose a trip and fall safety hazard as well as permitting foreign matter to fall easily into the pipe casing so as to later interfere with the intended access use. In field and unattended sites, there is the added hazard of unauthorized operation of the devices within the casing or its destruction. If access to the interior is easy, children may fill the casing with stones or trash for amusement, and thus cause the expenditure of much time and effort to clear the pipe casing before normal use may again be made of it.
Several methods for controlling access to the interior of a pipe casing are available, but all have varying advantages and disadvantages. Threaded covers may be employed, but due to the large sizes often necessary, such threaded caps tend to be heavy and bulky and require large wrenches to operate. It is also difficult and expensive to cut and protect the necessary matching threads at the casing terminus. Plugs of wood or other material may be used to close the opening, but these are relatively easy to remove unless they are deeply driven. Plugs also project beyond the end of the pipe with consequent interference and poor appearance.
It is desirable, therefore to provide an easily installed, and removable cap for pipe openings which will cover the openings securely and be locked in place, flush with the end of the pipe. It is further desirable to have such a cap be equally suitable for use with pipe casings which terminate a ground level or above ground, and be lockable with a simple tool at a point on the exterior of the cap.